6.5.1.3 D120A alanine-scanning mutagenesis 652387 6.5.1.3 D135A about 5% of the ligation activity of wild-type enzyme, mutant enzyme displays 4% of the adenylyltransferase activity observed with wild-type enzyme 662241 6.5.1.3 D244A site-directed mutagenesis 652429 6.5.1.3 D292A no ligation activity 662241 6.5.1.3 D292E about 10% of the ligation activity of wild-type enzyme 662241 6.5.1.3 D308A about 70% of the ligation activity of wild-type enzyme 662241 6.5.1.3 D425N lethal mutation 676215 6.5.1.3 D65A inactive 748777 6.5.1.3 D726A lethal mutation 676215 6.5.1.3 D95A the mutant shows RNA 3'-P guanylylation activity 748777